A plague from above | On this day

It’s not just a story from the Bible: thirty years ago, thanks to unprecedented weather conditions, a massive swarm of locusts crossed the Atlantic and ended up in the Caribbean. James Ferguson investigates how, and what became of them

Since Biblical times, locusts have been feared for the damage they can do to crops. Photo by Catchlight Lens/Shutterstock.com

A plague of locusts is not something to be taken lightly. When, in the Book of Exodus, God was threatening Pharaoh in order to force him to let the Israelites escape slavery in Egypt, He had a number of unpleasant sanctions in mind: frogs, lice, hail, boils, and locusts. “They will cover the face of the ground so that it cannot be seen. They will devour what little you have left after the hail, including every tree that is growing in your fields.”

God was, of course, referring to the desert locust (Schistocerca gregaria), one of Creation’s less thought-through products. Plagues of these voracious creatures have been making a misery of the lives of farmers in the Middle East and Africa for thousands of years. Eating their own weight in vegetation each day, their arrival can spell disaster for almost any crop, ranging from rice to bananas.

Locusts are most destructive when swarming in large groups (hence their Latin name), and can number up to a hundred billion in a vast cloud covering as much as 1,200 square kilometres. The swarming process, which transforms the normally solitary insect into a tiny part of a ravenous horde, usually occurs after a period of drought, and is an aerial search for vegetation. As the locusts swarm, they reach up to two thousand metres in altitude, carried along by winds, and covering up to two hundred kilometres per day. They have gone as far north as Spain and Russia, and as far south as Kenya and Nigeria.

With this in mind, you might be excused for thinking that with nearly five thousand kilometres of ocean separating the west coast of Africa and Barbados, the Caribbean would be safe from any locust-related plague. But you would be wrong. Thirty years ago, in early October 1988, the first-ever reported arrival of desert locusts in the region took place, due in large part to unprecedented meteorological conditions.

The previous month had witnessed the devastating arrival of Hurricane Gilbert, which left a trail of destruction from the Windward Islands to Jamaica, before crashing into Mexico and Central America. A total of 318 people lost their lives and damage worth an estimated US$2.98 billion was recorded between 8 and 19 September. But nature, it seemed, had not finished its destructive work. A series of tropical storms and depressions followed, including Hurricane Joan, which developed off the African coast on 5 October and ravaged the region from 15 October to 2 November.

According to one theory, the development of Joan coincided with locust swarms moving from the desert of Mauritania towards fertile Senegal, at which point strong winds blew many of the insects out to sea. “Swarms take flight during the day, increasing the possibility that thermal updrafts will carry the insects to high altitudes where they can be transported by fast-moving, upper-level wind currents,” said Professor Nathan Lovejoy of the University of Toronto. Pointing to another African coast tropical disturbance on 9 October, Calvin R. Grey of Jamaica’s National Meteorological Service observed that “It took six days for the Atlantic crossing, a distance of about three thousand miles. Fast-moving indeed. Now, a low-level jet of 29 to 40 miles per hour was associated with this tropical wave and the wind speeds decelerated rapidly on reaching the Windward Islands, possibly allowing the locusts to drop down in that area.”

Vast swarms had been reported in the Cape Verde islands, and then ships further west in the Atlantic radioed news of sightings. The first evidence of their arrival was the infestation of an AMOCO oil platform thirty miles off the east coast of Trinidad, followed by further cases of positive identification in a dozen more islands. A subsequent report by the Inter-American Institute for Co-operation in Agriculture estimated that around one hundred million locusts had made the journey, with St Vincent and the Grenadines and Dominica worst affected. One of six swarms arriving in Dominica was thought to have numbered twenty million.

Anxiety among regional governments was understandable. According to journalist Canute James, “The agriculture sector is the main support behind the domestic and export economy in most countries in the eastern Caribbean. Agriculture accounts for 28 per cent of gross domestic product in Dominica, 22 per cent in Grenada, and 14 per cent and 17 per cent in St Lucia and St Vincent, respectively.”

But, despite these alarming numbers and statistics, damage was limited. In Dominica, the locusts fed on coconut and cedar trees and on some crops, but time was against them. There, and across the wider region, they began to disappear rapidly after a period of five to ten days. Their extinction seemed to be based on several factors. They were exhausted after their transatlantic odyssey and unable to recover. They were victims of local predators, especially cattle egrets and blackbirds, which feasted on this gastronomic novelty. Above all, they were out of their environmental comfort zone in the moist, tropical, and post-hurricane climate of the Caribbean. Desert dwellers, they were simply not cut out for a life in the islands.

Yet the mystery remained of how the locusts had managed, for the first time in recorded history, to travel across the Atlantic. Certainly the exceptional weather conditions, with strong westerly winds propelling them from Africa, was a vital factor. But there was another, rather more grisly, hypothesis discussed in National Geographic News in December 2005:

Another possibility is that locusts flying at the front of the swarm may have become exhausted and died in the ocean, forming floating mats of dead insects. Other members of the swarm could have landed on these mats.

“Locusts are quite cannibalistic, so it seems very likely that they could have fed upon the corpses below, thereby obtaining enough energy to sustain additional flight,” said Greg Sword, a research ecologist with the US Department of Agriculture.

Sword had interviewed Barbadians who reported that masses of dead locusts had been washed up on beaches for several days in November 1988, thereby supporting this hypothesis. “Because a single swarm can contain billions of locusts, it could create a series of ‘rafts of the dead’ and still contain enough live insects to reach the Americas in large numbers.”

In any case, this particular plague was to prove short-lived in a region prone to other natural threats, not least hurricanes. But to return to plagues, Exodus, and the Israelites: it seems that locusts have become the snack of choice since an invasion in March 2013, in — Israel. Considered kosher, the insects are now receiving a taste of their own medicine, as they are farmed then deep-fried and devoured. You can even buy them ready-prepared under brand names such as Crunchy Critters.

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